The ability to develop a high efficiency lithium battery has been met with limited success owing in large part to low capacity, as measured in milliampere hours per gram (mAh/g), as well as a dramatic decrease in capacity with battery cycling. A prototypical anode for many lithium ion batteries is conventional graphite with a theoretical gravimetric capacity of 372 mAh/g. In response to these limitations, the prior art has explored metallic and metal oxide based anodes as a replacement for graphite. Such anodes typically have theoretical gravimetric capacities much greater than that of graphite. By way of example, tin has a theoretical gravimetric capacity of about 960 mAh/g. Tin oxide has a theoretical gravimetric capacity of 1491 mAh/g. Unfortunately, metal and metal oxide based lithium ion battery electrodes suffer from large volume changes with lithium intercalation/deintercalation that rapidly fragment the electrode with cycling. Electrode fragmentation also referred to herein as decrepitation increases overall cell impedance. As a result, bulk tin foil can only be cycled at 600 mAh/g for only about 15 cycles before a dramatic decrease in operating performance. S. Yang et al. Electrochem. Commun. 2003, 5(7), 587-590. In order to address bulk material decrepitation, nanostructures and nanocomposites have been extensively investigated to address volumetric changes during electrochemical cycling.
In order to overcome decrepitation problems associated with bulk tin, various composite systems have been evaluated. These systems illustratively include tin dispersed in carbon matrices (M. Egashira et al., J. Power Sources, 2002, 107(1), 56-60); tin-core/carbon-sheath coaxial nanocables (B. Luo et al, Adv. Mater. 2012, 24(11), 1405-1409); dual metal alloy nanoparticles encapsulated in carbon (Q. Fan et al. Electrochem. Solid-state Lett. 2007 10(12) A274-A278); tin-secondary metal oxides (Y. Idota et al., Science 1997, 276(5317), 1395-1397); tin oxide nanoparticles (C. Kim et al., Chem. Mater. 2005 17(12), 1397-3301); and other reduced domain size tin oxide halo structures, nanotubes, nanowires, and nanosheets. While these prior art records have shown progress in increasing gravimetric capacity to between 400 and 700 mAh/g over 15 cycles, these systems have required high carbon contents of greater than 40 percent by weight carbon in order to achieve improved capacity and at the expense of a lower theoretical gravimetric capacity than could be achieved with lower amounts of carbon materials.
Thus, there exists a need for a composition with a higher gravimetric capacity than conventional electrode materials. There further exists a need for a process for forming such a composition into a battery electrode.